Frederick w



F. W. MOFFAT.

ELECTRIC HEATING ELEMENT.

APPLICATION mm APR 12. 19:8.

1,323,084. Patented Nov. 25, 1919.

INVENTUE E74 B 2W? FREDERICK W. MOFFAT, OF WESTON, ONTARIO, CANADA.

ELECTRIC HEATING ELEMENT.

Specification of Letters Patent.

Patented Nov. 25, 1919.

Application tiled April 12, 1918. Serial No. 228,225.

To all whom it may concern Be it known that I, FREDERICK W. Mor- FAT, of the town of Weston, in the county of York, Province of Ontario, Canada, have invented certain new and useful Improvements in Electric Heating Elements, of which the followin is a specification.

This invention re ates to heating elements of the disk type in which the resistance wire is spirally arranged and connections with the terminals require to be made at the under side of the disk, and my object is to devise an element of this type in whiclr the connections of the resistance wire to the terminal posts are completely protected without increasing the diiiiculty of manufacture or assembly.

I attain my objects by means of the constructions hereinafter described and illustrated in the accompanying drawings in which-- Figure 1 is a plan view of the under side of the resistance carrying disk of an electric heating element constructed in accordance with my invention;

Fig. 2 a section on the line 1; and

Fig. 3 a section on the line 0cl in Fig. 1 showing also the metal containing pan.

In the drawings like numerals of reference indicate corresponding parts in the different fi res.

(2-4) in Fig.

1 is a isk of suitable insulating material such as commonly employed in the construction of electric heating elements. This disk is spirally grooved at its upper surface, preferably two grooves 2 being employed, each wound with a separate resistance. Each groove at the center of the disk communicates with a hole 3 extending through to the bottom of the disk. Each of these holes communicates with a oove 4 formed in the under side of the dis and extending to a recess 5 adjacent the edge of the disk. One or more bridges 6 are preferably formed over the grooves.

At the outer end of each groove 2 a hole 7 is formed extending through to the under side of the disk. About each of these holes is formed a recess 8. A block 9 of suitable insulating material is provided with a projection 10 adapted to fit into the recess 5 and to fill the same as exactly as possible consistent with an easy fit. The block is secured in place by means of the terminal 12,

passing through both the disk and the block and formed as a bolt.

Through the block are formed the holes 13, through which the wires 11 are led, being secured to the terminal at the under side of the block.

14 are blocks, each provided with a projection 15 adapted to fit into one of the recesses 8. Each of these blocks has a hole therein adapted to aline with the corresponding hole 7. Through these holes the connecting wires 16 from the outer ends of the resistance coils are led and are connected to the corresponding terminals 17, which are formed as bolts passing through the disk and blocks and holding the latter in place.

The disk is as usual fitted into a metal pan 18 containing heat insulating material and through holes in the bottom of the pan the terminal blocks ass. See Fig. 3. The connections where t ey lie in the grooves 4 have thus always been well protected but have not been so well protected adjacent the terminals, but it will be seen that with the constructions described the connections of the resistance wires are completely protected adjacent their points of connection with the terminals, so that no part can accidentally contact with any part underneath the element in such a way as to cause danger.

It will be understood. of course, that the number of the terminal blocks employed will depend on the number of separate resistances employed. It only one resistance wire is coiled on the surface of the disk, two blocks only will be necessary. With more separate resistance circuits a larger number might be employed. For the sake of standardization all blocks will be made from the same mold so that each block will be provided with two holes for the passage of the connections though in the case of the blocks 14 only one is essential.

What I claim as my invention is 1. In an electric heating element. the combination of a disk of insulating material adapted at its upper side to receive a resistance and having two holes formed therein for the passage of resistance connections to the underside of the disk, recesses being formed in the underside of the disk with which said holes communicate; blocks of insulating material separate from the disk provided with projections adapted to fit into said recesses; terminal bolts passing through the disk and the blocks and serving to secure the latter in place, holes being provided in the blocks alming with the aforesaid holes in the disk and resistance wiring carried at the upper side of the disks having its ends brought down through the holes in the disks and blocks and connected with the terminal bolts at the under side of the blocks.

2. In an electric heating element, the combination of a disk of insulating material adapted at its upper side to receive a resistance and having two holes formed therein adjacent its outer edge and two holes at the center for the passage of resistance connec tions to the under slde of the disk, recesses being formed in the underside of the disk with which said first mentioned holes oommunicate; and a third recess also adjacent the edge communicatin with two grooves formed in the undersi e of the disk and leading to the central holes; blocks of insulating material separate from the disk provided with projections adapted to fit into said recesses;terminal bolts passing through the disk and the blocks and serving to secure the latter in place, holes being provided in the blocks allning with the aforesaid holes in the disk and resistance wiring carried at the upper side of the disks having its ends brought down through the holes in the disks and blocks and connected with the terminal bolts at the under side of the blocks.

3. In an electric heating element, the combination of a disk of insulating material adapted at its upper side to receive a resistance and having a hole formed therein adjacent its outer edge and a hole at the center for the passage of resistance connections to the under side of the disk and a groove leading from the central hole to a pomt adjacent the outer edge of the disk; two blocks of insulating material se arate from the disk each having a hole t erein extending from top to bottom in alinement with the groove and hole respectively; terminal bolts passing through the disk and blocks and serving to secure the latter in place and resistance wiring carried at the upper side of the disks having its ends brought down through the holes in the disks and blocks and connected with the terminal bolts at the under side of the blocks.

Signed at Toronto, Canada, this 3rd day of April, 1918.

FREDERICK W. MOFFAT. 

